_nitrate_1.jpg) | |||
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| Identifiers | |||
|---|---|---|---|
3D model (JSmol) | |||
| ChemSpider | |||
| ECHA InfoCard | 100.030.210 | ||
| EC Number |
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| RTECS number |
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| UNII | |||
| UN number | 1469 | ||
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| Properties | |||
| Pb(NO3)2 | |||
| Molar mass | 331.2 g·mol−1 | ||
| Appearance | colorless or white | ||
| Density | 4.53 g/cm3 | ||
| Melting point | 470 °C (878 °F; 743 K)[2] decomposes | ||
| |||
| −74×10−6 cm3/mol[1][page needed] | |||
Refractive index (nD) | 1.782[2] | ||
| Thermochemistry | |||
Std enthalpy of formation(ΔfH⦵298) | −451.9 kJ.mol−1[1][page needed] | ||
| Hazards | |||
| GHS labelling:[5] | |||
    [3] | |||
| Danger | |||
| H272,H302+H332,H317,H318,H332,H351,H360Df,H372,H373,H410 | |||
| P203,P210,P220,P260,P261,P264+P265,P270,P271,P272,P273,P280,P301+P317,P302+P352,P304+P340,P305+P351+P338,P317,P318,P319,P321,P330,P333+P317,P362+P364,P370+P378,P391,P405,P501 | |||
| NFPA 704 (fire diamond) | |||
Threshold limit value (TLV) | 0.05 mg/m3[3] (TWA) | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | 93 mg/kg (rat, oral)[3] | ||
LDLo (lowest published) | 500 mg/kg (guinea pig, oral)[4] | ||
| NIOSH (US health exposure limits):[6] | |||
PEL (Permissible) | 0.050 mg/m3 (as lead) | ||
REL (Recommended) | 0.050 mg/m3 (TWA, 8h, as lead) | ||
IDLH (Immediate danger) | 100 mg/m3 | ||
| Safety data sheet (SDS) | ICSC 1000 | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Lead(II) nitrate is aninorganic compound with thechemical formulaPb(NO3)2. It commonly occurs as a colourlesscrystal or white powder and, unlike most other lead(II)salts, issoluble inwater.
Known since theMiddle Ages by the nameplumbum dulce (sweet lead), the production of lead(II) nitrate from either metalliclead orlead oxide innitric acid was small-scale, for direct use in making otherlead compounds. In the nineteenth century lead(II) nitrate began to be produced commercially in Europe and the United States. Historically, the main use was as a raw material in the production ofpigments forlead paints, but such paints have been superseded by less toxic paints based ontitanium dioxide. Other industrial uses included heatstabilization innylon andpolyesters, and in coatings ofphotothermographic paper. Since around the year 2000, lead(II) nitrate has begun to be used ingold cyanidation.[citation needed]
Lead(II) nitrate istoxic and must be handled with care to prevent inhalation, ingestion and skin contact. Due to its hazardous nature, the limited applications of lead(II) nitrate are under constant scrutiny.[by whom?]
Lead nitrate was first identified in 1597 by thealchemistAndreas Libavius, who called the substanceplumbum dulce, meaning "sweet lead", because of its taste.[7] It is produced commercially by reaction of metalliclead with concentratednitric acid in which it is sparingly soluble.[8][9] It has been produced as a raw material for making pigments such aschrome yellow (lead(II) chromate,PbCrO4) andchrome orange (basic lead(II) chromate,Pb2CrO5) andNaples yellow (lead antimonate, (Pb2Sb2O7)). These pigments were used fordyeing[dubious –discuss] and printingcalico and other textiles.[10] It has been used as an oxidizer inblack powder and together withlead(II) azide in specialexplosives.[11]
Lead nitrate is produced by reaction oflead(II) oxide with concentrated nitric acid:[12]: 388
It may also be obtained by evaporation of the solution obtained by reacting metallic lead with dilute nitric acid.[13]
Solutions and crystals of lead(II) nitrate are formed in the processing of lead–bismuth wastes from lead refineries.[14]
-nitrate-xtal-Pb-coordination-3D-bs-17.png)
Thecrystal structure of solid lead(II) nitrate has been determined byneutron diffraction.[15][16] The compound crystallizes in the cubic system with the lead atoms in aface-centred cubic system. Itsspace group is Pa3Z=4 (Bravais lattice notation), with each side of the cube with length 784 picometres (7.84 Å).
The black dots represent the lead atoms, the white dots the nitrate groups 27 picometres (0.27 Å) above the plane of the lead atoms, and the blue dots the nitrate groups the same distance below this plane. In this configuration, every lead atom isbonded to twelve oxygen atoms (bond length: 281 picometres (2.81 Å)). AllN−O bond lengths are identical, at 127 picometres (1.27 Å).[17]
Research interest in the crystal structure of lead(II) nitrate was partly based on the possibility of free internal rotation of the nitrate groups within the crystal lattice at elevated temperatures, but this did not materialise.[16]
Lead nitrate is an oxidizer and has been used as such inpyrotechnics.[11][19]
Basic nitrates are formed when alkali is added to a solution.Pb2(OH)2(NO3)2 is the predominant species formed at lowpH. At higher pHPb6(OH)5NO3 is formed.[20] The cation[Pb6O(OH)6]4+ is unusual in having an oxide ion inside a cluster of 3 face-sharingPbO4 tetrahedra.[12]: 395 There is no evidence for the formation of the hydroxide,Pb(OH)2, in aqueous solution below pH 12.
Solutions of lead nitrate can be used to form co-ordination complexes. Lead(II) is ahard acceptor; it forms stronger complexes withnitrogen andoxygen electron-donating ligands. For example, combining lead nitrate andpentaethylene glycol (shortened to EO5 in the referenced paper) in a solution ofacetonitrile andmethanol followed by slow evaporation produced the compound [Pb(NO3)2EO5].[21] In the crystal structure for this compound, the EO5 chain is wrapped around the lead ion in an equatorial plane similar to that of acrown ether. The two bidentate nitrateligands are intrans configuration. The totalcoordination number is 10, with the lead ion in a bicappedsquare antiprismmolecular geometry.
The complex formed by lead nitrate with abithiazole bidentate N-donor ligand is binuclear. The crystal structure shows that the nitrate group forms a bridge between two lead atoms.[22] One aspect of this type of complex is the presence of a physical gap in thecoordination sphere; i.e., the ligands are not placed symmetrically around the metal ion. This is potentially due to alone pair of lead electrons, also found in lead complexes with animidazole ligand.[23]
Lead nitrate has been used as a heat stabiliser in nylon and polyesters, as a coating forphotothermographic paper, and inrodenticides.[12]: 388
Heating lead nitrate is convenient means of makingnitrogen dioxide:
In thegold cyanidation process, addition of lead(II) nitrate solution improves theleaching process. Only limited amounts (10 to 100 mg lead nitrate per kilogram gold) are required.[24][25]
In organic chemistry, it may be used in the preparation ofisothiocyanates fromdithiocarbamates.[26] Its use as abromide scavenger duringSN1 substitution has been reported.[27]
Lead(II) nitrate is toxic, and ingestion may lead to acute lead poisoning, as is applicable for all soluble lead compounds.[28] All inorganic lead compounds (but not elemental lead) are classified by theInternational Agency for Research on Cancer (IARC) asprobably carcinogenic to humans (Category 2A). They have been linked torenal cancer andglioma in experimental animals and to renal cancer,brain cancer andlung cancer in humans, although studies of workers exposed to lead are often complicated by concurrent exposure toarsenic.[29] Lead is known to substitute forzinc in a number ofenzymes, includingδ-aminolevulinic acid dehydratase (porphobilinogen synthase) in thehaem biosynthetic pathway andpyrimidine-5′-nucleotidase, important for the correct metabolism ofDNA and can therefore cause fetal damage.[30]
-nitrate-unit-cell-3D-balls.png)
-nitrate-xtal-3D-SF.png)
